有任何疑问或需要帮助，请通过邮件或社交平台联系我们。您的反馈是我们改进的重要动力。 Oxygen also helps make up nearly all of Earth’s oceans by mass. A water molecule (H2O) is created up of two hydrogen atoms and a person oxygen atom. Even though you will find additional hydrogen atoms in h2o, hydrogen has fewer mass. By mass, h2o includes nearly 90% oxygen. https://trumank357kfa3.bloggerbags.com/profile